Cowl for chimneys or ventilator shafts



July 4, 1950 T. A. LEARDI ET AL COWL FOR CHIMNEYS OR VENTILATOR SHAF'TS Filed Aug. 2, 1946 S m s w N www m m 5N7 L05 L AJ 7 5 Patented July 4, 1950 UNITED STAT S GOWLFORGHIMNEYSAOB; VENTILATOR. 1

SHAFTS Thomas Augusto Leardi, London, Edmund John Long, County Durham, and Maurice Jack Stephens, Catford London, England Application August 2, 1946, SerialNo. 688,080

In Great-Britain-lulyi, 1945 Section 1, Public Law 690, August 8, 1946 Patentexpires July 5, 1965 4 Claims.

This invention relates to COWlS-ifOl. fiues, chimneys or ventilator shafts and has for an object to provide an improved cowl bywhich the possibility of down-draughts occurring in the flue, chimney or ventilator shaft issubstantially eliminated.

According to the present invention a cowl for a flue, chimney or ventilator shaft comprises, a pipe member for mounting the cowl at the end of the flue, chimney or ventilator shaft, said pipe member having a nozzle-like outlet end portion, a plurality of hollow, open-ended, frusto-conical shields carried on the end of the pipe member above said end portion in vertically superposed relationship, each shield having its narrower end uppermost, each shield except the uppermost shield having its narrower end projecting into and inwardly spaced from the wider end, of the shield next above, and the said, outlet end portion of the pipe member projectinginto and being inwardly spaced from the wider end of the lower most shield, a plurality of open-ended vent pipes secured externally on the uppermost shield in cireumferentially-spaced relationship, each vent pipe extending downwardly and outwardly from the uppermost shield and communicating at its upper end through a vent hole into the interior of the uppermost shield at a level spaced above the narrower end of the shield next below the uppermost shield, and a conical baflle member supported to be wholly within the uppermost shield and above the shield next below and having its apex downwards and its part of maximum diameter level with said vent holes.

Preferably two frusto-conical shields are provided.

One construction of cowl of this invention will now be described by way of example, the description having reference to the accompanying drawing which The figure is a perspective view of one construction of this invention partly broken away to show the internal details.

Referring to the drawing, a cowl suitable for preventing down-draught in a chimney flue or. ventilator shaft, comprises a length of pipe H3 by which the cowl is mounted at the end of the flue or shaft. The pipe I is illustrated as being circular but the lower end thereof may be of any convenient cross section.

The upper end of the pipe I I] has a nozzlelike outlet ll provided by a tapered portion l2 and carries in superposed relation thereon a plurality of hollow-open-ended frusto-conlcal shields, illustrated as two shields whereof the lower shield is indicated by reference numeral 13a and the upper shield by reference-numeral I329, which shields" are provided around their lower edges with integral lugs 14 by which the shields are secured to the pipe It or the shield next below it. The number of shields l3 maybe varied, but preferably two, such shields are pro--- vided. The shields l3 are arranged so as to be partially nested, that is with, their narrower ends located within but in spaced circumferential relation to the Wider end of the shield next above. Likewise the tapered end l2 of the pipe it] is located within and in spaced circumferential relation to the wider end of the lowermost shield Hm. I

The upper shield I3b is shown as. being of greater length than the lower shield l3a. but having substantially the same upper and lower diameters. At the upper end of the upper shield. l3b are, secured bent-over lugs l5 having slots Hi therein within which slide vertical rods 51 carrying at their lower ends an inverted conical baffle H3. The rods l1 are bent over at the upper ends and are of such a length that the baffle I8 is normally held above the open end of the lower shield l3 and has its widest part level with a series of vent holes l9 formed in the upper shield Hit. The base dimensions of the baffle [8 are preferably substantially equal to or slightly greater than the dimension of the smaller end of shield l3a and of the outlet ll. Secured on the outer surface of shield I31) are a series of downwardly and outwardly directed vent pipes 20 which shroud and terminate at their inner ends in the vent holes l9. The number of vent holes I!) and vent pipes 20 may be varied as desired but conveniently a series of three is provided. The lower ends of the vent pipes are cut at right angles to the cowl axis.

The cowl as described above has been found substantially to reduce down-draughtand under test to give an upward flow of air through pipe I0 even when located in an air current directed downwardly thereon.

The baffle I8 is supported for axial movement in the upper shield I3b to facilitate cleaning of the cowl. This arrangement permits a sweeps brush to enter the upper shield l3b to beyond the level of the vent holes I 9.

We claim:

1. A cowl comprising a pipe member for mounting the cowl at the end of the flue, chimney or ventilator shaft, said pipe member having a nozzle-like outlet end portion, a plurality of hollow, open-ended, frusto-conical shields carried on the outlet end portion of the pipe member projecting into and being inwardly spaced from the wider end of the lowermost shield, a plurality of openended vent pipes secured externally on the uppermost shield in circumferentially-spaced relationship, each vent pipe extending downwardly and outwardly from the uppermost shield and communicating at its upper end through a vent hole into the interior of the uppermost shield at a level spaced above the narrower end of the shield next below the uppermost shield, and a conical bafile member supported to be wholly within the uppermost shield and above the shield next below and having-its apex downwards and its part of maximum diameter level with said vent holes.

2. A cowl as claimed in claim 1, wherein the vent pipes have their lower ends cut at right angles to the cowl axis.

3. A cowl comprising a pipe member for mounting the cowl at the end of a flue, chimney or ventilator shaft, said pipe member having a nozale-like outlet end portion, a first hollow, openended frusto-conical shield carried on the pipe member above said end portion with its narrower end uppermost, the said end portion of the pipe member projecting into and being inwardly spaced from the wider end of said first frustoconical shield, a second hollow, open-ended frusto-com'cal shield carried on said first frustoconical shield vertically above it, said second frusto-conical shield having its narrower end uppermost, and said first frusto-conical shield having its narrower end projecting into and inwardly 4 spaced from the wider end of the second frustoconical shield, a plurality of open-ended vent pipes secured externally on said second frustoconical shield in circumferentially-spaced relation, each vent pipe extending downwardly and outwardly from the second frusto-conical shield and communicating with the interior of the second-frusto-conical shield through vent holes located at a level spaced above the narrower end of the first frusto-conical shield, and a conical bailie member supported to be wholly within the second frusto-conical shield and above the narrower end of the first frusto-conical shield and having itsapex downwardly directed and its parts of maximum diameter level with said vent holes. 4. A cowl as claimed in claim 3, wherein the vent pipes have their lower ends out at right angles to the cowl axis.

THOMAS AUGUSTO LEARDI. EDMUND JOHN LONG. MAURICE JACK STEPHENS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

